The long-range objectives of this research are: (1) to develop a comprehensive theory of airflow in the larynx that will predict the pressure and velocity distributions and give an estimate of the aerodynamic forces inside the glottis; this will be useful not only in improving our understanding of phonation, but also as a direct application to computer simulation of speech production, (2) to investigate the effects of biomechanical properties of laryngeal tissues on fluid dynamics (the boundary effects); this will further our understanding of voice disorders caused by mechanical stresses and may be useful in future design and implementation of an artificial larynx. It is expected that a newly-developed computation technique will result in an accurate prediction of the velocity profile and aerodynamic forces in the glottis. Ultimately, the results of this investigation will be useful in the understanding the mechanisms of pitch, loudness, and quality control, and of the self-oscillation characteristics of the vocal folds. The study is both experimental and theoretical in nature. The first phase considers steady flow in the larynx. Experiments will be conducted to measure the air velocity and pressure in various plexiglass models of the larynx, and in canine excised larynges. Also, a numerical model will be developed to solve the equations of motion through laryngeal airways. Experimental data of phase one and data from biomechanical studies of laryngeal tissue will be used to validate the theoretical model. Phase two will consider pulsatile flow, with and without tissue movements. Experiments will be conducted to measure the time dependence of velocity and pressure in the excised larynx and the plexiglass models. The theoretical model will be extended to predict the unsteady velocity and pressure distribution.